Grinding wheel truing mechanism



Feb. 21, 1956 2,735,420

GRINDING WHEEL TRUING MECHANISM Filed Oct. 22, 1954 5 Sheets-Sheet 1 l3 IO/l H 6 INVENTOR. ,l V /7 ALBERT H. DflLL BY 74a I Fl g Z flTTORNEYS.

Feb. 21, 1956 DALL 2,735,420

GRINDING WHEEL TRUING MECHANISM Filed OCT.- 22, 1954 5 Sheets-Sheet 2 INVENTOR. flLBERTH. DALL ATTORNEYS.

Feb. 21, 1956 A. H. DALL Filed Oct. 22, 1954 5 Sheets-Sheet 3 16 Fi 5 l 43 "23 0 v 66 5 iii 56 E 50 6/ E o I 55 53 .99 1 $1 I s INVENTOR. flLBE/FT H. DALI.

A T TORNE Y6;

United States Patent C GING WHEEL rnUiNo MECHANISM Albert H. Ball, Cincinnati, Ohio, assignor to The Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of Ohio Application October 22, 1954, Serial No. 463,954

7 Claims. (Cl. 125-11) This invention relates to improvements in grinding machines and has particular reference to centerless grinding machines and to the structure utilized in connection with abrasive wheel truing in connection with such machines.

One of the objects of the present invention is the provision of an improved form of mechanism for effecting generation or truing of non-uniform surfaces on abrasive wheels such as the regulating wheels utilized in connection with centerless grinders.

A further object of the invention is the provision of a truing mechanism for the purpose aforesaid which can be utilized for effecting either radial variations in the peripheral contour of the abrasive wheel or selected contour variations transversely of the effective surface of the wheel, and in which the control mechanisms may be utilized either individually or jointly in the formation of the ultimate wheel surface.

A further object of the invention is the provision of a truing mechanism particularly adapted for production of extremely accurate surfaces on what are known in the art as cam-shaped regulating Wheels and in which the operating mechanism may be of a power actuable type controlled at a point remote from the grinding throat of the machine.

Another object of the invention is the provision of an improved hydraulically controlled truing tool operating structure particularly adapted for use in the formation of variable or irregular surfaces on an abrasive wheel embodying independent mechanisms for primary determination of the circumferential and transverse shapes to be imparted during truing to an abrasive wheel surface, which structure embodies an interpreting mechanism for determination of the resultant eifect as respects truing tool positioning of the independently actuable surface determinators.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Figure 1 is a view in elevation of a centerless grinder embodying the present invention.

Figure 2 is a vertical section on the line 22 of Figure 1.

Figure 3 is an enlarged view of the truing tool plunger and associated supporting and actuating elements, taken as on the line 3-3 of Figure 2.

Figure 4 is a fragmentary plan view of the tuning slide portion of the grinding machine and associated elements.

Figure 5 is an enlarged view partially in section of the peripheral cam controlled portion of the truing mechanism viewed as on the line 55 of Figure 2.

Figure 6 is a diagrammatic View of the mechanical and hydraulic elements for control of position of the truing tool plunger.

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In the drawings the numeral 1t) designates the bed of a centerless grinder supporting within the housing 11 the grinding wheel 12 adapted to be operated at a suitable grinding speed. Carried by the bed is the primary slide 13 on which is mounted the workrest support 1 5 for the workpiece 15. Carried by the slide 13 is the regulating wheel slide 16 adjustable by screw 1'7 and including a journal portion 18 forthe regulating wheel spindle 19 supporting at one end the regulating wheel 21 Rigidly secured to the regulating wheel slide 16 is the wheel guard 21 having ways 22 mounting and guiding the truing slide 23 for movement transversely of the periphery of the regulating wheel 20. Piston rod 24 having one end coupled to the slide 23 and the other extending to piston 25 in cylinder 26 couples the slide to the reciproeating hydraulic motor constituted bythe parts 25--26 for imparting a back and forth movement to the slide.

Mounted for vertical movement on slide 23 by the antifriction bearings 27 is the valve bushing 28 hearing at its lower end roller 29 translatable across the upper edge of the cam or template 30 mounted on hood 21. The spring 31 reacts against the bushing to hold the same downward with its roller or follower 29 at all times maintained in engagement with the cam 30.

For hydraulic operation of the present invention, use has been indicated of the pressure pump 32 for supply of hydraulic actuating medium into the conduit 33 at a pressure controlled by the bypass relief valve 34. The pressure conduit 33 has a branch conduit 33A ported into the upper end of the hydraulic cylinder portion 35 of the bushing 28 and a second bypass branch 36 ported into the flow control area 37 of the bushing.

Slidable within the bushing is the valve stem 33 having the intermediate groove 39 disposed in the space 37 of the bushing and the tapered throttle portion 50 variably positionableas the stem is shifted to control the discharge from 36 through the space 37 to the control conduit 41.

At its lower end the valve stem extends into the cylinder chamber 35' and is provided with the piston portion 42. The area of the piston circumsciibing the stern and subject to the action of pressure introduced through conduit 33A is preferably one-half the area of the lower side of the piston against which reacts pressure from the branch conduit 43 which extends from conduit 41 and is ported into the lower end 35' of the cylinder.

For control of the respective pressures existing in the upper and lower ends of the cylinder 35, use is made of the hydraulic transducer designated as an entirety by the reference character 4-4. The conduit ilt is ported into the interior bore of the transducer 45 while slidabie in this bore is valve spool 46 downwardly urged indicated in Figures 5 and 6 by the spring 47. The spring urge is limited by contact of the roller 48 on the lower end of the valve with abutment 49 on the L-shaped arm 5t) pivoted at 51 to the regulating Wheel slide 16.

As shown in Figure 5, the arm 56; is provided with ways 52 for the abutment slide 53 adiustable along the arm by screw 54 and carrying the fulcrum roller or contact 55 for engagement with the L-shaped arm 55. The arm 56 is pivoted at 57 and extends into overlying relation with the contour cam 53 secured to the rear or left hand end of the wheel spindle 19 for rotation in synchronism with the spindle and the wheel 20 to be trued or shaped. Mounted on the slide unit 16 as shown in Figure 5 is a bracket 6b slidably supporting the rod 61 which passes downward through the aperture 62 in the right hand end of lever 56. Mounted on the rod and interposed between the bracket 60 and arm 62 is a spring 63 urging the arm downward to maintain the stylus or follower 64 carried by the arm in engagement with the periphery of cam 58. Rod 61 is provided with a knob 65 by which the rod and arm may be raised, lifting follower 64 out of engagement with the cam, the rod being provided with an abutment spline 66 engageable with the upper surface of the bracket upon upward movement and rotation of the rods to lock the parts in raised position. It will be noted that adjustment of the slide 53 relative to the arm 50 varies the reaction on valve 46 for the same amount of movement of the follower 64.

In the valving arrangement, as shown in detail in Figures 3 and 5, and in combined relationship in the hydraulic diagram, Figure 6, it will be noted that the main pump pressure in the conduit 33-33A reacts in the upper end of cylinder 35 against an area of piston 42 which for practical purposes may be one-half the effective area of the piston in the lower portion of the cylinder. When the resistance afforded by the taper or throttle 49 of the valve to flow from 36 into 41 is equal to the resistance to flow past throttle 67 on valve 46 which controls the discharge of pressure fluid from the bore of the transducer to the zero pressure or low pressure reservoir return conduit 68, the pressure in 43 reacting against the lower end of the piston will be one-half the pressure in 33A reacting against the upper end of the piston and the rod 38 will be in a stabilized position.

In transition adjustment from the lower portion of the template 58 as at to the portion 71 of the template of greater radius, the follower 64 will be moved upward, causing an outward swinging of arm 56 as viewed in Figure 5. This outward swinging of arm 55, permits clockwise swinging movement of the arm 59 and consequent downward movement of the follower 48 and valve 46, reducing the resistance to discharge from 43 into 68 and accordingly reducing the pressure against the lower end of the piston 42. Such reduced resistance will immediately react, permitting greater flow from 36 to 41 and a consequent drop in pressure in the upper chamber 72 of the truing tool control cylinder 73. Slidable in cyiinder 73 is piston 74 having a rod 75 reducing the effective piston area in chamber 72 to one-half the effective piston area in the lower chamber 76. Piston 74 is biased upwardly by the spring 77 while the pressure in the lower cylinder 76 is controlled by way of the conduit 78 which extends to the selector or reversing valve 79 supported on the truing slide 23.

The valve 79 includes a bushing portion 80 having pressure inlet port 81 longitudinally spaced as respects the conduit 78 and to which is coupled the pump pressure conduit 33B. Longitudinally spaced from conduit 78 in the opposite direction is discharge conduit 82 containing variable throttle 83 for regulating the flow from discharge conduit into the general reservoir conduit system 68.

Slidable in the bushing 80 is a spool valve 84 having a central groove or cannelure at 85 disposed in registration with the conduit 78 and the pair of tapered throttles 86 and 87 movable by shifting of the valve to control the flow through the pressure port 81 or discharge port 88 to which the conduit 82 is coupled.

This valve has a stem 89 provided with a roller 96 engaging the flange 91 on the feedback control link or lever 92. This lever, as is indicated in Figures 3 and 6, has one end pivoted at 93 to the valve stem 38 and its opposite end pivoted at 94 to the vertically movable holder 95 which carries the truing tool 96 for properly forming the contour of the abrasive wheel 20. Suitable connections, such as indicated at 97, join the piston rod 75 and truing tool holder 95' so that vertical movement of the holder 95 corresponds to the controlled corresponding movement of piston 74.

Downward movement of roller 64 as when riding on a receding portion or portion of shorter radius of cam 58 as indicated at 70 in Figure 5, will permit clockwise rocking of bellcrank lever or arm 56 due to action of spring 63. This movement will react through arm 50 to move spool 46 upward. This tends to close throttle 67, increasing the resistance to flow from 41 to 68, and thus a rise in pressure 4 in the hydraulic system 41-43 and the lower cylinder area 35'. This rise in pressure in the lower cylinder area 35' will effect an upward movement of the piston 42 the valve stem 38 and the left hand end of link 92 as viewed in Figures 3 and 6, correspondingly moving the flange 91 and permitting a follow-up movement of valve stem 89 and valve 84 as actuated by spring 98. Such upward movement of the valve 84 will decrease the throttle resistance at 87, relieving pressure in 78 which is then connected by throttle to the reservoir conduit 82 while at the same time the upward movement of the throttle portion 40 will increase resistance to by-pass flow from pressure conduit 36 and consequently an increase in pressure in the cylinder area 72, the combined results effecting a controlled downward movement of the piston 74 and the coupled truing tool holder 95. As the truing tool moves downward, pivot 94 will carry down with it the right hand end of the link 92, depressing valve 84 to close throttle 8'7, blocking flow from 78 to 82 to stop the downward movement of the truing tool holder. Conversely, if the roller 64 and arm 57 are moved upwardly when engaged by a portion of the cam 58 of greater radius as has been illustrated in Figure 5, arm 58 will swing in a clockwise direction. This allows follower 48 and spool 46 to move downward and the throttling action at 67 will be decreased. This decrease in throttling action causes a pressure drop in the conduit system 41-43 and cylinder 35 so that the pressure introduced through 33A into the upper cylinder portion 35 will assume control and the valve stem 38 is moved downward. This will move the left hand end of link 92 down, opening throttle 86, permitting flow of actuating medium through pressure conduit 338 into 78, tending to raise piston 73 and the truing tool holder, while at the same time this downward movement of stem 38 will decrease the throttling effect at 40 by opening of the throttle, permitting greater by-pass of actuating medium from the conduit 33 coupled with the area 72 above piston 73 and a consequent pressure drop, permitting upward movement of the piston until such time as the reverse or upward rocking of the right hand end of the connecting link will allow the valve 84 to move up into pressure shutoff position as respects the conduit 78.

In the foregoing, consideration has been given particularly to the action which takes place in connection with actuation of the follower 64 by the contour of the cam 58 rotating in synchronism with the rotation of the abrasive wheel being trued. In this connection, attention is particularly invited to the fact that due to the system of motion transmitting levers, indicated in Figure 5, the member 55 may be adjusted downwardly with respect to the lever 50 to a location close to the pivot 57 so that an appreciable oscillatory movement of the arm 56 about pivot 57 will result in but a slight axial adjustment of the valve 46 and therefore a slight variant only in the position of the throttle 67. In the particular adjustment of parts indicated, the movement ratio is approximately 1 to 3, but this ratio can be changed by adjustment of the slide 53, varying the responsiveness of the valve to lever actuation. By the movements aforesaid, determination is made of the peripheral or circumferential contour produced on the abrasive wheel by the truing devices. Additionally, the control valving aforesaid serves simultaneously to determine the transverse contour of the periphery of the wheel as the truing tool is reciprocated across the wheel by the piston cylinder mechanism 2526. During such movement the roller 29 rides on the contoured upper face of the template 30 variably to position the valve bushing 28.

Upward or downward movement of the bushing as controlled by movement of the roller 29 in opposition to the force of the spring 31 will move with it the contained hydraulically locked valve stem 38, tilting the link 92 for varying the position of valve 84, efiecting what might be termed a base point or zone adjustment of the position of the member 95, which is subject to additional positional variation in accordance with the movements of valve 46.

It will be noted that rimarily the position of them-emher" 38 within the sh'iftable' bushing is determined by the pressureconditions'above and below the piston 42. However, should there by any resistance to movement of the member 38 when the bushing 28 is being shifted, upward movement of the bushing will tend to open the discharge port to 41 adjacent the throttle 40 causing an increase in pressure below the piston 42, raising the member38 to its hydraulically balanced neutral position. Corresponding'ly, downward movement of the bushingv 28 effected by drop in the contour of the cam 30, as the bushing is shifted by spring 31, will tend to close the throttle at 40 so that there will be a pressure drop in the lower chamber and the pressure in 33A will efiiect a power shifting of the member 38 in the direction of bushing movement.

It will further be understood that the control cams 30 and 58 are at all times individually effective as respects the particular followers engaging the cams but that their combined reaction as respects the valve 84- is a resubant or the bodily movement imparted to the unit 2838 and the independent relative movement of the parts 28 and 38 under control of the valve 46. Consequently, the actual effective position at any moment during the truing operation of the truing tool 96 with respect to the axis of the rotating abrasive wheel being trued is the resultant of the reactions of these independent position determining factors.

From the foregoing description it will be evident that in the present invention there has been provided what may be termed a hydraulic linear translator for determination of the position of the truing tool. This linear translator consists of two spool type valve resistances in series, one constituting the sender and the other the receiver. If, as shown, these resistances are made alike, and the control valves are correspondingly positioned with respect to their ports, the resistances within the valves to fluid flow will be equal, and if one valve, such as the valve 44, is ported direct to reservoir, the pressure between the resistances, as in the conduit 43, will be one-half the input pressure in the conduit 33 so that if the upper area of piston 42 is one-half the lower area its controlled valve normally will be held in a static balanced position. Likewise, if the valve in the sender or transmitter 44 is moved to vary the resistance to discharge to reservoir the pressure between the resistances changes and the receiver throttle 45 will be power moved toward the position which will cause the half pressure to be reestablished. Thus, for every movement of the transmitter there is a corresponding movement of the receiver which is, in turn, transmitted through the link 92 to valve 84. This power transmittal determines the movement of the truing tool actuating piston 74, and at the same time the link serves as a feedback to valve 84, reestablishing its neutral position and stopping movement of the piston when the amount of shifting determined by the transmitter or by bodily movement of the receiver has been completed.

It will be understood that the follower 64 may be made of any desired form or size according to the niceties of the contour of the cam 58 to be followed. In the present instance it has been shown as a roller carried by the stud or yoke 98 and positionally adjustable with respect to arm 56 by suitable means such as the screw 99.

It is further to be understood that while the control mechanism may be utilized for all positionings of the truing tool 96, that in some instances, as Where an appreciable portion of the abrasive wheel 20 is to be trued concentrically, a positive position controlling mechanism as respects a maximum diameter constant contour control be utilized. This may take the form of a lug or offset portion 100 on the truing tool holding member 95 positioned for engagement by the adjustable stop 101 mounted on the bracket or yoke 102 carried by the block 103 forming a part of the general truing slide 23. Adjustment of the stop I01 serves variably to limit the outward or re tracting movement of the Ming tool holding member and thus establish a definite retracted position for the uuing tool 96 irrespective of the hydraulically elfected lifting action exerted against the piston 74. In this manner the tru-ing tool is most rigidly locked for insuring con stant position of same during the concentric wheel truing operation.

What is claimed is:

1. In a grinding machine, a support, a rotatable wheel spindle journaled in the support, an abrasive wheel carried by the spindle for rotation thereby, and means for producing a contour on the-surface of the abrasive wheel including a templatecarried by the shaft for rotation therewith, a template follower carried by the support and mounted for movement relative to the support, a truing tool mounted on the" support for movement in a direction toward and from the abrasive wheel, a tool actuating hydraulic motor, a source of hydraulic pressure, and means for variably controlling the reaction of the hydraulic pressure on said hydraulic motor including a first conduit coupling the source of pressure to one side of said hydraulic motor, a second conduit coupled to the other side of said hydraulic motor, a movable selector valve for alternatively connecting the second conduit to the source of pressure or'to exhaust, a movable by-pass valve coupled with the first conduit for controlling the pressure in said conduit, and means connecting said selector valve and said by-pass valve for varying the position of the selector valve in accordance with movement of the bypass valve.

2. In a grinding machine, a support, a rotatable wheel spindle journaled in the support, an abrasive wheel carried by the spindle for rotation thereby, and means for producing a contour on the surface of the abrasive wheel including a template carried by the shaft for rotation therewith, a template follower carried by the support and mounted for movement relative to the support, a truing tool mounted on the support for movement in a direction toward and from the abrasive wheel, a tool actuating hydraulic motor, a source of hydraulic pressure, and means for variably controlling the reaction of the hydraulic pressure on said hydraulic motor including a first conduit coupling the source of pressure to one side of said hydraulic motor, a second conduit coupled to the other side of said hydraulic motor, a movable selector valve for alternatively connecting the second conduit to the source of pressure or to exhaust, a movable by-pass valve coupled with the first conduit for controlling the pressure in said conduit, means connecting said selector valve and said bypass valve for varying the position of the selector valve in accordance with movement of the bypass valve, an operating cam, a cam follower engaging the cam, means mounting the cam and follower for relative traversing movement whereby the position of the follower will be varied in accordance with the contour of the cam, and means connecting said cam follower and bypass valve for operating said valve as the position of the follower is varied.

3. In a grinding machine, a support, a rotatable wheel spindle journaled in the support, an abrasive wheel carried by the spindle for rotation thereby, and means for producing a contour on the surface of the abrasive wheel including a template carried by the shaft for rotation therewith, a template follower carried by the support and mounted for movement relative to the support, a truing tool mounted on the support for movement in a direction toward and from the abrasive wheel, a tool actuating hydraulic motor, a source of hydraulic pressure, and means for variably controlling the reaction of the hydraulic pressure on said hydraulic motor including a first conduit coupling the source of pressure to one side of said hydraulic motor, a second conduit coupled to the other side of said hydraulic motor, a movable selector valve for alternatively connecting the second conduit to the source of pressure or to exhaust, a movable by-pass valve coupled with the first conduit for controlling the pressure in said conduit, and means connecting said selector valve and said by-pass valve for varying the position of the selector valve in accordance with movement of the by-pass valve, said by-pass valve including a hydraulically actuable piston and 9. containing cylinder for the piston, and the valve operating means including a hydraulic pressure conduit coupled with me cylinder, and means for varying the pressure in said conduit.

4. In a grinding machine, a support, a rotatable Wheel spindle journaled in the support, an abrasive Wheel carried by the spindle for rotation thereby, and means for producing a contour on the surface of the abrasive wheel including a template carried by the shaft for rotation therewith, a template follower carried by the support and mounted for movement relative to the support, a truing tool mounted on the support for movement in a direction toward and from the abrasive wheel, a tool actuating hydraulic motor, a source of hydraulic pressure, means for variably controlling the reaction of the hydraulic pressure on said hydraulic motor including a first conduit coupling the source of pressure to one side of said hydraulic motor, a second conduit coupled to the other side of said hydraulic motor, a movable selector valve for alternatively connecting the second conduit to the source of pressure or to exhaust, a movable by-pass valve coupled with the first conduit for controlling the pressure in said conduit, means connecting said selector valve and said by-pass valve for varying the position of the selector valve in accordance with movement of the bypass valve, an operating cam, a cam follower engaging the cam, means mounting the cam and follower for relative traversing movement whereby the position of the follower will be varied in accordance with the contour of the cam, means connecting said cam follower and by-pass valve for operating said valve as the position of the follower is varied, said by-pass valve including a hydraulically actuable piston and a containing cylinder for the piston, and the valve operating means including a hydraulic pressure conduit coupled with the cylinder, and means for varying the pressure in said conduit.

5. In a grinding machine, a support, a rotatable wheel spindle journaled in the support having an abrasive wheel supporting portion, a truing tool mounted on the support for movement toward and from said porton, a piston and cylinder mechanism for effecting said toward and from movement of the truing tool, a source of actuating pressure, a pressure conduit ported into the cylinder at one end of the piston, a second conduit coupled into the cylinder at the other end of the piston, a pressure bypass valve coupled to the pressure conduit, said valve comprising two movable parts, namely a movable spool and a movable bushing, a pair of control cams, means coupling one of said cams with the bushing for variably positioning same, means coupling the other cam with the spool for independently variably positioning the spool, said coupling means including followers individual to the respective cams, and means to efiect relative traversing movement of the cams and followers for positioning of the spool and bushing.

6. In a grinding machine, a support, a rotatable wheel 8 spindle journaled in the supporthaving an abrasive wheel supporting portion, a truing tool mounted on the support for movement toward and from said portion, a piston and cylinder mechanism for efiecting said toward and from movement of the truing tool, a source of actuating pressure, a pressure conduit ported into the cylinder at one end of the piston, a second conduit coupled into the cylinder at the other end of the piston, a pressure by-pass valve coupled to the pressure conduit, said valve comprising two movable parts, namely a movable spool and a movable bushing, a pair of control cams, means coupling one of said cams with the bushing for variably positioning same, means coupling the other cam with the spool for independently variably positioning the spool, said coupling means including followers individual to the respective cams, means to eitect relative traversing movement of the cams and followers for positioning of the spool and bushing, a selector valve coupled to the second conduit, pressure and exhaust conduits coupled to said valve, said valve having a portion movable selectively to connect said second conduit to a pressure or an exhaust conduit, and means connecting one of the movable parts of the bypass valve with the movable portion of the selector valve for actuation thereof.

7. In a grinding machine, a support, a rotatable wheel spindle journaled in the support having an abrasive wheel supporting portion, a truing tool mounted on the support for movement toward and from said portion, a piston and cylinder mechanism for effecting said toward and from movement of the truing tool, a source of actuating pressure, a pressure conduit ported into the cylinder at one end of the piston, a second conduit coupled into the cylinder at the other end of the piston, a pressure bypass valve coupled to the pressure conduit, said valve comprising two movable parts, namely a movable spool and a movable bushing, a pair of control cams, means coupling one of said cams with the bushing for variably positioning same, means coupling the other cam with the spool for independently variably positioning the spool, said coupling means including followers individual to the respective cams, means to effect relative traversing movement of the cams and followers for positioning of the spool and bushing, a selector valve coupled to the second conduit, pressure and exhaust conduits coupled to said valve, said valve having a portion movable selectively to connect said second conduit to a pressure or an exhaust conduit, means connecting one ofthe movable parts of the bypass valve with the movable portion of the selector valve for actuation thereof, said means comprising a link intermediately engaging the selector valve and having one end movable by the part and the other movable by the controlled piston and cylinder mechanism, whereby upon movement of either the part or the mechanism the link will react on the selector valve variably to position said valve.

References Cited in the file of this patent UNITED STATES PATENTS 

